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<head><meta charset="utf-8"><title>simd_bitmask bug · t-compiler/wg-llvm · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/187780-t-compiler/wg-llvm/index.html">t-compiler/wg-llvm</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/187780-t-compiler/wg-llvm/topic/simd_bitmask.20bug.html">simd_bitmask bug</a></h3>

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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/187780-t-compiler/wg-llvm/topic/simd_bitmask%20bug/near/236584423" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Caleb Zulawski <a href="https://rust-lang.github.io/zulip_archive/stream/187780-t-compiler/wg-llvm/topic/simd_bitmask.20bug.html#236584423">(Apr 28 2021 at 21:31)</a>:</h4>
<p>Hi all, not sure if this is the right place for this question,</p>
<p>I'm running into a bug with the <code>simd_bitmask</code> intrinsic on MIPS: <a href="https://github.com/rust-lang/stdsimd/pull/99/checks?check_run_id=2415305187">https://github.com/rust-lang/stdsimd/pull/99/checks?check_run_id=2415305187</a></p>
<p>This intrinsic is effectively integer truncation followed by a bitcast from &lt;i1 x N&gt; into a single integer.  On MIPS it gets the bit order wrong (reversed).  Does anyone think this is perhaps correct?  Or a bug in LLVM?</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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